This invention relates generally to medical imaging and, more particularly, to methods and apparatus for the classification of nodules.
The present invention concerns a process of automatic detection and classification of nodules in a tomographic image of an anatomical zone of a patient, and also a tomodensimetric medical imaging system permitting such a detection method to be implemented.
An application of such a method of particular interest is in the field of medical imaging, and in particular in oncology, especially for the early detection of lung cancers by the early detection and classification of pulmonary nodules. The early detection of nodules has a direct influence on the rate of survival of patients to a term of five years. At the present time, the rate of survival to five years can reach or even exceed 80%, while for a late detection the rate of survival falls to about 10%.
It is generally accepted that the growth of cells of a malignant tumor is on the whole exponential. Thus a method of detecting cancers consists of monitoring the growth of a suspect lesion. A technique permitting the implementation of this method consists of determining and monitoring the size of pulmonary nodules.
Historically, this monitoring was performed using two-dimensional images and evaluating the size of the module by using a measuring system with two coordinates.
It can be understood that an improvement consists of examining the nodules by using a tomographic image of the lung, that is, a three-dimensional image. This method of medical imaging enables an organ to be examined using x-rays, plane by plane, while measuring by means of detectors, differences of density of x-ray absorption by the biological tissues. Data coming from these detectors are processed by a processor for reconstituting in three dimensions the image of the organ examined. Thus, tomographic imaging constitutes a tool providing valuable aid for the early detection of cancers.